Conventionally, buckets, forks and other tools are mounted on the jib or arm of a hydraulic excavator by locating a pair of pins in aligned bores provided on the free end of the jib and the rear face of the bucket. As the buckets are relatively heavy and the clearances between the pins and bores are small, changing an excavator bucket can be a difficult and time consuming operation requiring a second person to assist the excavator operator. In view of these difficulties there have been a number of proposals for hitches which are secured on the end of the jib and which allow a bucket to be mounted or released from the jib in a relatively straightforward "one-man" operation. Examples of such hitches are described in U.S. Pat. Nos. 5,082,389 and 5,179,794. The disclosed hitches include mutually perpendicular recesses for receiving pins or crossbars provided on the bucket. The jib is first moved relative to a bucket resting on the ground such that a first pin is positioned in a respective forward recess. The hitch is then rotated on the jib to lift the bucket and bring the other pin into the rear recess. In U.S. Pat. No. 5,082,389 a spring biassed closure member is deflected inwardly by the pin as it moves into the rear recess and then returns to an extended position to partially close the recess and trap the pin. A hydraulic piston and cylinder assembly may be provided for retracting the member and releasing the pin. In another embodiment the closure member is biassed towards the retracted position while a piston and cylinder assembly is used to extend the member. In U.S. Pat. No. 5,179,794, movement of the second pin into the recess actuates a pawl to release a spring biassed wedge member which retains the pin in the recess.
It is among the objects of aspects of the present invention to provide a hitch which allows a bucket to be mounted on an excavator jib in a one-man operation and which has a bucket retaining arrangement which minimises the risk of unintentional release of a bucket from the hitch.